One method of repairing damaged sewer pipe is to excavate the area surrounding the sewer pipe and replace the broken portion. This is a very expensive and a labor intensive solution and is also an inconvenience to residents living in the area and utilizing roadways overlying the area.
Another solution is In situ relining of sewer pipes. In situ methods typically utilize a resin coated liner which is inserted into the existing sewer pipeline and unrolled against the sewer pipe. The unrolled liner is held against the existing sewer pipe while the resin cures to form a new pipe lining within the existing pipe.
One example of such a method is shown in U.S. Pat. No. 4,366,012. In this patent a process utilizing an elongated outer tube having an inner tube comprised of felt is shown. Uncured resin is introduced into the tube and is used to impregnate the felt inner tube. The two concentric tubes are then inverted into the end of the sewer pipe to be repaired and the inversion process continues until the area of the sewer pipe needing repair has been reached by the inverting tubes. Upon inversion the impregnated felt liner is placed on the outside of the original outer liner, and is pressed against the interior surface of the sewer pipe. When the resin cures a new pipe liner is provided at the area to be repaired by this process.
The applicant's co-pending patent application shows a method for impregnating a curable resin in a layer of resin absorbent material located within an elongated flexible bladder tube having a fill end and a vacuum end positioned down stream from the fill end. The bladder tube includes two walls forming a tube cavity therein. The layer of resin absorbent material has a down stream end positioned a predetermined distance from the vacuum end of the bladder tube, and an upstream end. An elongated gas conduit having first and second conduit ends is placed within the tube cavity with the first conduit end positioned up stream from the down stream of the resin absorbent material and with the second conduit end positioned down stream from the down stream end of the resin absorbent material.
A quantity of curable resin is then introduced into the fill end of the bladder tube, the quantity of resin being sufficient to impregnate all of the resin absorbent material within the bladder tube. A vacuum source is then connected to the bladder tube at a point spaced down stream from the down stream end of the resin absorbent material whereby the wall of the bladder tube will collapse on the layer of resin absorbent material and the gas conduit will provide a path for evaluating gas through the collapsed two walls. Gas is continuously evacuated from the bladder tube until the curable resin moves to the down stream end of the absorbent material and completely impregnates the absorbent material.
As described in detail in the co-pending '817 application, the repair sleeve is attached at its forward end to an inversion collar by means of stitches. The forward end of the inversion collar is then affixed to the forward end of the bladder tube by heat sealing, adhesive, or other suitable securement. In this way, as the bladder tube in inverted, the inversion collar will also be inverted so as to be positioned on the outside of the bladder after the inversion. Similarly, the stitches connecting the inversion collar to the repair sleeve will also cause the repair sleeve to invert, so as to be positioned on the outside of the bladder tube in contact with the portion of the pipeline to be repaired.
While the method and apparatus for repairing pipelines as described in the co-pending '817 application has served well for portions of continuous pipeline, the procedure and apparatus for repairing a junction of a lateral with a main line has been difficult, and has required access to the distal end of the lateral.
It has been discovered that access to main sewer lines for residential or other customers was frequently accomplished by forming a hole in the main line with a sledge or the like. The lateral was then simply abutted against the hole, and then the excavation backfilled to cover the juncture. Obviously, this juncture of the lateral with the main line would typically leak, and would not provide a tight sealed connection.
With the growing concern regarding the environmental impact of sewage leakage, such junctures are of primary concern for repair.